Dome type chimney top



R. L. STONE ETAL DOME TYPE CHIMNEY TOP May 18, 1965 2 Sheets-Sheet 1 Filed Nov. 8, 1962 FIE--2- MEW ON Y O E WWW m w m Don ME G wmfi DAG y 1965 R. L. STONE ETAL 3,183,822

DOME TYPE CHIMNEY TOP Filed Nov. 8, 1962 2 Sheets-Sheet 2 INVENTORS RICHARD L. STONE BY GEORGE R. CUNNINGTOMJIE.

A TTORNE Y United States Patent 3,183,822 DOME TYPE CHIMNEY TOP Richard L. Stone, Palo Alto, and George R. Cunnington, In, Los Altos, Calif'., assignors to William Wallace I Corporation, Belmont, Calif, a corporation of Delaware Filed Nov. 8, 1962, Ser. No. 236,457 4 Claims. (Cl. 98-83) This invention relates to an improved end cap or top for use on chimneys or ventilator pipes or lines and one especially adaptable for use in combination with prefabricated metal chimneys or vent pipes.

In vent pipes and chimneys a top or end cap is essential in order to protect and shield the vent or chimney opening from the influx of foreign material or rain as well as to provide a draft inducing ar aspirating effect under all types of wind conditions. A primary object of the present invention is to provide an improved vent cap that fulfills all of these requirements.

Another object of the invention is to provide an improved chimney or vent top that produces an aspirating effect to assure good draft control; that enables the free unobstructed escape of gases; and yet one that protects the vent or chimney opening from any scoop effect with wind gusts approaching the top from any angle so that a steady draft through the chimney is assured.

Another object of the invention is to provide a vent or chimney top that maintains the aforementioned satisfactory aspirating efiect and yet prevents any rain, birds or other foreign debris from entering or clogging the top; and moreover, a top which when used on a chimney Will also prevent the efilux of sparks.

Still another important object of the present invention is to provide an end cap or top for vents or chimneys that performs well the vital functions of protection and draft control and yet is unusually simple in form and thus readily adaptable for ease and economy of manu facture.

A further object of the invention is to provide a vent cap or top having a clean attractive appearance and one that is generally compatible with a wide range of architectural style.

Other objects, advantages and features of the invention will become apparent from the following detailed description taken in conjunction with the drawings, in which:

FIG. 1 is a View in perspective showing a top embodying the principles of the present invention in a typical installation;

FIG. 2 is an enlarged plan view of the top shown in FIG. 1 with a portion of its dome broken away;

FIG. 3 is an enlarged view in elevation and in section of the chimney top of FIGS. 1 and 2 shown attached to a prefabricated metal chimney in accordance with the invention;

FIG. 4 is a greatly enlarged fragmentary view in elevation and in section showing a portion of the top of FIGS. 1-3;

FIG. 5 is an enlarged fragmentary plan view of a gas vent top embodying the principles of the invention with a portion broken away to show a protective grille;

FIG. 6 is a view in elevation and in section of the gas vent top of FIG. 5;

FIG. 7 is a view in section taken along the line 7-7 of FIG. 5.

Referring to the drawings, FIG. 1 shows a chimney terminal or top 10 embodying the principles of the invention as it appears when installed on the end section of a typical prefabricated metal chimney 11. Broadly speaking, the top comprises the unique combination of three aerodynamically functional parts, a dome shaped cover 12, a cylindrical band 13 located below the cover 3,183,822 Patented May 18, 1965 12, and a downwardly divergent frusto-conical collar 14 attached to and extending radially outwardly from the band 13. These elements as arranged in accordance with the invention, cooperate to provide an improved level of performance under a wide range of conditions as well as other important advantages.

The dome-shaped cover 12, which may be formed from sheet metal is circular in plan form and provides several important functions. One function is to prevent falling rain or debris from entering the open end of the chimney or vent pipe. A second function of the cover 12 is that of providing a chamber 15 in which the air or gas flowing upward from the chimney or vent pipe can expand and slow down so that it can be diverted smoothy by the curvature of the outer peripheral dome portion and then expelled from the top without causing turbulence or flow resistance.

A third important function of the dome cover 12 is to provide an aspirating efiect that increases the draft through the chimney or vent pipe when a wind blows against the top.

In accordance with the principles of the invention, the dome cover 12 has a diameter considerably greater than the cylindrical band .13 and is positioned so that its pheripheral edge 15 is situated substantially in the same plane as the upper end of the .band 13 and form an annular discharge opening 16 at its upper end. In a wind prevailing against the top the dome-shaped cover 12 acts as an .air foil that is situated directly over the end of the chimney or vent pipe, since the band 13 is adapted to fit around the end of the chimney section. The flow of wind over the curved streamlined cover 12 creates an aerodynamic condition of reduced pressure and thereby generates a suction at the discharge opening 16.

The aspirating or suction effect created by the dome cover 12 is stable for winds from slightly above to slightly below horizontal. Ascending winds approaching the top If) from below are deflected by the collar 14 and its size can be varied when desired to adjust performance. Generally, it should have a diameter equal to or only larger than the cover dome 12, and when positioned below the dome-shaped cover 12, it deflects ascending winds away from the cover and the discharge opening 16 and thereby obviates any scoop effect which could cause back drafts through the chimney. For winds striking the top It) from above, the cover 12 shields the lower collar 14 and obviates any scoop effect for descending winds. From the foregoing it is apparent that the combination of shielding from both above and below, in conjunction with the aforementioned aerodynamic shape of the dome, produces a uniform draft over the complete span of wind directions.

The cylindrical band 13 serves to provide the necessary separation between the cover 12 and the collar 14 which shields the discharge opening 16. It also forms an enlarged chamber 17 Within which the gas or air exiting from the chimney or vent pipe can initially expand to reduce any turbulence or fiow resistance before entering the chamber 15 under the cover 12 where it is diverted and then discharged.

In the embodiment of the invention shown in FIGS. 13, the dome cover 12 is connected to the cylindrical band 13 and to the collar 14 by means of metal supports 18 that are spaced apart circurnferentially and extend downwardly from the cover dome 12. The supports 18 may be attached to the cover 12 by some suitable means such as rivets or by spot welding and they are similarly attached to the band 13 at circumferentially spaced apart locations near its upper edge.

Inside the centrally located band 13 near its lower edge is fixed an annular coupling adapter member 19 having a cross sectional shape that enables it to fit over and par- Q) tially around the end member of a prefabricated metal chimney Ill. The adapter 39 is particularly suited for connection with a prefabricated metal chimney of the typedescribed in our co-pending application Serial No.

770,190, filed on October 28, 1958, now abandoned. In

FIGS. 3 and 4 such a chimney construction is shown having an end coupler 2t 1 Theadapter ring member 19 has an inner axially directed iiange 21 and an outer cylindrical portion 22 which is riveted or spot welded as indicated by the numeral23 to the lower end of the cylindrical band 13. Extending radially outwardly from the outer cylindrical portion 22 is a flange 24 to which is spot welded a radial upper flange 25 on the collar member 34. T o attach the top 1% shown in FIG. 3 it is merely placed down over the end of the chimney section 11 with the adapter member 19 within the band 13 fitting snugly over the end coupler 26 of the chimney.

In another embodiment of the present'invention, as shown in FIGS. and '6 a top 3% is connected to a double walled gas vent pipe 31. It has the basic combination of components according to the'invention, namely, a

dome-shaped cover 32, a downwardly diverging collar 33, and a band 34, but in addition thereto it is provided with other novel features. The band 34; instead of being cylindrical, is tapered upwardly and has a lower frustoconical portion 35 that forms a solid circumferential wall whose upper edge formed by a shoulder 36 is substantially co-planar with or somewhat lower than the lower edge 37 of the cover 32. Attached to the lower band portion 35 is an upper portion 38 having an increased taper which is provided with a peripheral flange 39 that is attached by rivets 40 or by spot welds to the cover 32 near its lower edge 37. The upper portion 38 of the band 34 comprises a grille with circular bars 41 and circumferen tially spaced apart openings 43 that are sufiiciently narrow so that they will prevent the influx of all foreign material such as by birds in the chimney orvent pipe 31. For chimneys the openings 43 may be made smaller to prevent the'discharging of sparks. V

In the embodiment of FIGS. 5' and 6 the upper band portion 38 having the grille and the lower band portion 35 are preferably formed as one integral member by a sheet metal stamping method. T o render additional strength to the band 34 and its connection to the cover 32, a knee-type support member 44 is formed at each spaced apart bar member 42. As shown in FIG. 7, each support member 44 has a channel cross section which is tapered towards its ends on both the upper and lower band portions 35 and 38.

The collar 33 is attached to the lower edge of the band 34 in any suitable manner. As shown in FIG. 6, a flange 45 extending radially inwardly is formed on the lower edge of the band 34 and the inner edge 46 of the collar 33 is attached thereto by spot welding or riveting and curled partially around it. Wrapped around the curled edge 46 of the collar 33 is a curled upper edge .17 of a cylindrical pipe stub 43 which is adapted to fit snugly down inside the double walled vent pipe 31.

With both of the embodiments of the invention the air or gas exiting from the end of the chimney or vent pipe first expands into the region formed at the upper end of the band. This reduces the velocity and controls the flow resistance of the unit. The chimney gases continue to expand and slow down as'they pass into the region 15 beneath the dome-shaped cover 12 or 32 and are then diverted smothly and expelled at the annular discharge opening 16.

In this way flow resistance is minimized in the presentinvention by means of a short expansion and a smoothly contoured turn.

.To those skilled in the art to which this invention relates, many changes in construction and widely diflering embodiments and applications of the inventionwill suggest themselves without departing'fro'm the spirit and scope of the invention. The disclosures and the descripi. above a building roof, said device comprising tion herein are purely illustrative and are not intended to be in any sense limiting.

We claim:

l. A terminal device adapted to be connected to the end of a fixed prefabricated double walled conduit extending above a building rout, said device comprising in combination: V

a single wall band forming a central section; an upper cover member having a generally oblated semispheroidal shape extending over and rigidly connected to saidconduit section, said cover member thereby forming an annular discharge opening to said terminal device. around the upper end of said conduit section; 1

and means attached to said central section for connecting it to the end of said double walled conduit, said means comprising an annular adapterring attached to the inner wall of said central section, said ring having an edge flange adapted to fit inside the end of said double walled conduit;

a downwardly sloping annular collar member fixed near the lower end or said central section;

said cover member and said collar member both having a diameter substantially larger than said central section and being thereby adapted to shield the opening to said terminal device from the direct influx of ascending and descending wind gusts while providing minimum resistance to the flow of gases from the double walled conduit as well as a strong uniform aspirating effect at said discharge opening.

2. The terminal device as described in claim 1 wherein said band forming said central section has a cylindrical shape.

3. A chimney top adapted to be connected to the end of a prefabrictaed metal chimney extending above a roof, said top comprising, in combination: 1

a generally cylindrical central section; an up er cover member having a generally oblated semispheroidal shape extending over and rigidly connected to said conduit section, the'outer edge of said cover member being substantially in the same plane as the upper edgeof said central section, said cover member thereby forming an annular discharge opening to said chimney top around the upper end of said central section; a and means attached to said central section for connecting it to the end of said double walled conduit,

said means comprising an annular adapter ring attached to the inner wall of said central section, said ring having an edge flange adapted to fit inside the end of said double walled conduit; downwardly divergent frusto-conical annular collar member fixed near the lower end of said conduit section;

said cover member and said collar member both having a diameter substantially larger than said central section and being thereby adapted to shield the opening to said top from the direct influx of ascending and descending wind gusts While providing minimum resistance to the flow of gases from the chimney as well as a strong uniform aspirating effect at said discharge opening.

4. A terminal device adapted to'be connected to the end of a fixed prefabricated metal conduit extending in combination: 1

a sheet metal central member having an impervious generally tubular lower portion and an upwardly divergent and pervious upper portion integral. there- 7 with, said upper portion comprising a plurality of integral interconnected annular and longitudinal grille members;

anjupper dome shaped'cover member having a generally oblated seini-spheroidalshape with an outer edge extending beyond the upper edge of the divergent upper portion of said central member, an annular discharge opening to said terminal device being thereby formed by the open spaces between said grille members in the upper pervious portion of said central member;

means rigidly connecting the upper portion of said central member to said cover member;

a downwardly sloping annular collar member fixed to and extending radially outwardly from the bottom edge of said central member;

said cover member and said collar member both having a diameter substantially larger than said central member and being thereby adapted to shield the discharge opening to said top from the direct influx of ascending and descending wind gusts;

a bottom edge flange on the lower portion of said central member extending radially inwardly, a curved annular portion on the inner edge of said collar member fixed to and curved around said flange;

and a cylindrical pipe stub having an upper edge portion curled around said annular portion on said collar.

References Cited by the Examiner UNITED STATES PATENTS ROBERT A. OLEARY, Primary Examiner. 

1. TERMINAL DEVICE ADAPTED TO BE CONNECTED TO THE END OF A FIXED PREFABRICATED DOUBLE WALLED CONDUIT EXTENDING ABOVE A BUILDING ROOF, SAID DEVICE COMPRISING IN COMBINATION: A SINGLE WALL BAND FORMING A CENTRAL SECTION; AN UPPER COVER MEMBER HAVING A GENERALLY OBLATED SEMISPHEROIDAL SHAPE EXTENDING OVER AND RIGIDLY CONNECTED TO SAID CONDUIT SECTION, SAID COVER MEMBER THEREBY FORMING AN ANNULAR DISCHARGE OPENING TO SAID TERMINAL DEVICE AROUND THE UPPER END OF SAID CONDUIT SECTION; AND MEANS ATTACHED TO SAID CENTRAL SECTION FOR CONNECTING IT TO END OF SAID DOUBLE WALLED CONDUIT, SAID MEANS COMPRISING AN ANNULAR ADAPTER RING ATTACHED TO THE INNER WALL OF SAID CENTRAL SECTION, SAID RING HAVING AN EDGE FLANGE ADAPTED TO FIT INSIDE THE END OF SAID DOUBLE WALLED CONDUIT; A DOWNWARDLY SLOPING ANNULAR COLLAR MEMBER FIXED NEAR THE LOWER END OF SAID CENTRAL SECTION; SAID COVER MEMBER AND SAID COLLAR MEMBER BOTH HAVING A DIAMETER SUBSTANTIALLY LARGER THAN SAID CENTRAL SECTION AND BEING THEREBY ADAPTED TO SHIELD THE OPENING TO SAID TERMINAL DEVICE FROM THE DIRECT INFLUX OF ASCENDING AND DESCENDING WIND GUSTS WHILE PROVIDING MINIMUM RESISTANCE TO THE FLOW OF GASES FROM THE DOUBLE WALLED CONDUIT AS WELL AS A STRONG UNIFORM ASPIRATING EFFECT AT SAID DISCHARGE OPENING. 